You can download it from the Galaxy store I believe but Samsung is moving away from that and going to Google messages which means the app probably won't be around much longer you're going to have to find another equivalent or use Google messages
While you still can download Samsung Messages from the Galaxy Store, you will not have RCS functionality. No read and send receipts, no reactions, no typing indicators, no high-resolution photos and videos, especially from Android to iPhone. IPhones in ioS 18 finally got RCS compatibility. The caveat is it will only work in Google Messages, in Samsung Messages it will only be SMS/MMS.
Also in one ui 7 there's support coming for 5g messages, hopefully this means samsung is stepping up to the plate and updating the messaging experience after all
